Electric core oven



Dect 8, F. A. COLEMAN ELECTRIC CORE OVEN Filed April 28, 1923 4Sheets-Sheet l Y2/@A127018 7 4W' 4. www El/m was Liu c Dec. 8, 1925.1.564.945

F. A. COLEMAN ELECTRIC CORE OVEN Filed April 28, 1923 4 Sheets-Sheet 2uw. s, 1925. 1.564.945

`F.A.COLEMAN "y ELECTRIC CORE OVEN Filed April 28. 1925 4 Sheets-Sheet 5@MMM Dec. 8, l925- 1.564.945

l F. A. COLEMAN- ELECTRIC CORE OVEN Filed April 28, 1925 f 4Sheets-Sheet 4 H JURA/Fys Patented Dec. 8, 14925.

UNITED STATES FREDERICK A. COLEMAN, F CLEVELAND, OHIO, ASSIGNOR, BYMESNE ASSIGNMENTS, A

PATENT OFFICE.

TO CARL W. SCHAEFER, 0F CLEVELAND, OHIO.

ELECTRIC CORE OVEN.

Application filed April 28, 192.3. Serial No. 635,378.

To all 'whom it may concern:

Be it known that I, FREDERICK A. COLE- MAN, 'a citizen of the UnitedStates, residing at Cleveland, in the county of Cuyahoga and State ofOhio, have invented a' certain Vnew and useful Improvement in anElectric Core Oven, of which the following 1s a full,

.- clear, and exact description, reference being had to the accompanyingdrawings.

This invention relates to. electric ovens such, for instance, as areused for baking cores.

The general object of the invention is the provision of an extremelyefficient heating oven. Valls of an electrically heated oven should bemade. of a material high in heat resisting properties and at the sametime of sufficient strength to insure a rigid structure. A preferred wayto accomplish this is to construct the oven walls of refractory materialand 'brace these walls by metal frames. However, in so doing, it hasbeen found that either the walls are compressed against each other attheir uncture resulting in crumbling effects, imperfectjoints, etc., orthe efficiency of thenoven is greatly reduced through the wastefulconduction of heat. from the ovens bythe frame members or through boltsconnecting such members. Y Y Y One of the objects of my invention is toeliminate the usual bolts and stays for holding'the structure togetherand which extend through the refractory walls. One of the problemssolved by my invention is of bracing each of' the individual wallmembers by a metal frame in such a way that no part of the metalframework is exposed to the heat within the oven.

Another object is the provision of a compact and durable heating elementin a core oven that may bev protected against fouling by the materialtol be heated and at the same time function at thel highest degree ofefficiency, the protective device serving to better distribute the heatto all parts of the oven. In cooperation with the heating element andprotective device, I have also provided a Ventilating shaft systemdesigned to distribute air currents within the chamber in a novel andvery effective manner.

A further object is the provision of a safety cutout for the hightension electric circuit, generally used in such ovens, which preventsthe operator from incurring physical harm by causing opening of theheating circuit whenever the elements are moved to accessible position.

Other objects will become apparent inthe following description of myinvention which refers to the accompanying drawings, and its essentialcharacteristicsare summarized in the claims.

In the drawings, Fig. l illustrates the preferred form of my inventionand is in the nature of a longitudinal central section through an entireoven; Fig. 2 is a sectional plan taken along the line 2 2 of Fig. 1showing the drawer supporting the heating elements; Fig. 3 is a verticalsection through the oven as indicated at 3 3 of Fig. l; Fig. t is a planview of the frame comprising the heating element support showing all butone of the elements removed therefrom: Fig. 5 is a` rear elevation of aportion df the oven wall showing the safety cutoutdevice; Fig. 6 is asectional plan through the cutout device taken along line 6 6 of Fig. 5;Fig. 7 is in the nature of a fragmentary perspective illustrating thefront, side and roof of the furnace and is broken away to show themanner in which the frame members retain and support the body of thewalls and roof; Fig. 8 is a wiring diagram showing the electricalconnection of the heating elements with the current supply and theprotective cutout switch.

Referring to the various parts by numbers, in Figs. l, 2 and 3, ldesignates the oven in general, which is made up of' side` front. andrear walls, designated 1U, l1 and l2, and ceiling and floor wall members1? and 14,- which are suitably retained and braced against each other bya skeleton frame work ofy metal channel and angle members to be laterdescribed.

It has been found convenient to use in this oven thc system of drawersfor holding the material to be heated such as shown at 20, consisting ofa lattice framework suitably braced, and being provided with rollers 21mounted on a through shaft 22, and a head portion 23.. Suitably bracedheat resisting material substantially closes the openings in the frontwall 11 of the oven through which the drawers are inserted. The latticeframework carries the material to be baked or heated. The drawers aresupported within the oven by a frame Q5 and ployed for this purpose.

are adapted to be withdrawn from the oven by suitable drawer engagingmechanism 30. Any convenient mechanism might be em- I have shown adepending beam carrying suitable drawer engaging members supported by atrolley 31, mounted on rollers 32 which are adapted to rest on channelrail members 33 rigidly supported` by the oven frame.

The heating elements are carried by a drawer similar in some respects tothe drawer 20. .Thisdrawer is mounted upon rollers and may be removedfrom the oven for repairs or cleaning in much the same manner. asthedrawers 20. This structure will be later described more in detail.

Referring to the walls, top and floor structure, as shown in Figs. 1, 2,3 and 7, it will be seen that I have made the walls, top and floor of-slabs of refractory material such as fire brick or'similar substanceand have assembled the slabs or sections in the following manner Theside walls, 10, Fig. 2, are contained within a frame work comprisingvertical and horizontal angle members 61, 62, 63 and 64. The rear wallis suitably held in position by vertical angle members 65 and horizontalangle members 67. Figs. land 3 show the roof 13 as retained by arectangu- 'lar frame structure comprising longitudinal angle members 68and transverse members 69 and 70. The front wall portion 11 is in thenature of a grille, comprising upright channel frame members 80 andcross bars formed of channels 81. These bars and uprights, it will benoted, support merely their own weight. hence acomparatively light frameis used which will conduct and radiate only aninsignificant quantity ofheat; The flanges of all these channels extend inwardly and arecompletely filled with heat resisting material as indicated at 82. Thecross bars form openings wherethrough the drawers are inserted. Afabricated T bar 66 is secured to the uprights 61 in such a manner as tooverlie the members 80 and retain the drawer frame in place.

It will be noted that the Walls 10-and 12 and the roof 13, haveprojections 14, 15 an .i

16 that extend over the inwardly projecting flanges of the angle membersthat form the frame, thus closing the corners against heat 'radiation byconductance through the angle members. Where it is inconvenient tousesuch projections as at the juncture of the side walls and the 'roof,.theflange of the angle stops short of projecting into the oven and theresulting crevice betweenthe wall and roof is filled with refractoryheat resisting material as at 64. The whole struc' 'ture may beconveniently tied. together at the corners by gusset plates 71 and 72 asshown in Fig. 7.

The car containing theheating elements,

the air inlet Ventilating shafts and protective baille lates inthe formI prefer and have found) satisfactory will now be described. i

The car frame, as shown in Fig. 4, is made up of side angle members 91,and front and rear angle members 92 and 93, respectively. A refractoryclosing block 95 isl interposed'between the frame member 92` anda plate96; suitable bolts, not shown, extending from the frame member to theplate will hold the structure together. The refractory materialsubstantially closes the lowermost opening in the Grid-like structureforming the front wall when the car is in position and a suitable anglemember 97, bolted to the upright frame members 61,

holds the car in place. Mounted on the car frame members are rollers 85supported in brackets u86 on the frame members 91, which rest on rails87 vin the form of channel members imbedded inthe floor 14 as shown inFi 3. L i pair of tubes 100, open at their outer end and provided withdampers 101, are suitably carried on the plate 96 at one end. Thesetubes extend within the oven beneath the c ar frame and are secured bymeans of U-bolts 102 to the frame member 93 at their rear end. .Arefractory plugfcloses this rear end of each tube. A long slot uniformlytapered toward the rear is cut intol the tubes as shown at 104 and iscut along an axial plane inclined 45 degrees from the vertical.

vThis is for directing the flow of air toward the central portion of theoven, it being found advantageous to so direct the air within thechamber to prevent excessive coolingV along the side walls while notsuiiiciently Ventilating the oven at the center. The any rotating thetubes, thus ai'ordin complete control of the air flow within thischamber. J.

The heating elements comprise coils of wire 110, wound upon suitablecylinders of insulatin material 111, which are in turn supporte by boltsor rods 112 and 113 insu atingly supported at their ends by channels115, best shown in Figs. 1, 3 and 4. The resistance heating strips orwires 110y are fastened directly to the bolts 112 and -113 gle ofdirection may be changed if necessary at their ends and convenient busbars 120,

vto better distribute the air currents and pre- 'vent material fromy thecore carrying drawers ositioned above from falling upon and fouhn theVheating elements.

Bri ging the channel or rail members 33- ber of the car supports the busbars'at their rearwardly extending ends and it will bc seen that theyproject through the rear wall 12 into a boxlike structure shown in Figs.1, 5 and 6 which carries a cutout switch and cable terminals.

In thediagram Fig. 8, A, lB, C, DI, E and F, indicate the heating coils.In order to balance the circuit two of the coils are shunted across eachphase of the circuit.

The coils A and D bridge the bus bars 121 and 122, the coils C and Fbridge the bars 120 and 122 while the remainin coils B and E connect thecombination of 121.

The universal circuit breaker 155 is so arranged as to disconnect allthe feed wiresv simultaneously from the current Supply, this beingindicated as a delta connection three hase circuit 156. The circuit 152in which 1s the safety switch 140, the solenoid 159, for operating theswitch 155 and a. manually controlled switch 158, is shunted across onephase of the supply and draws yonly a small amount of current.

In order to heat the oven the switch 158 is first closed, thus throughthe medium of the solenoid 159 closing the switch 155. The,

movement of the bar 150, occasioned by thus closing the circuit 152, isonly sufficient to close the main c1rcu1t. However, should an excesslveamount of current be drawn into l the circuit 152, the bar 160 moves thetoggle joint 161 over a dead center and a convenient spring 162 acts tobreak the heating circuit. rIfhis may also be done by opening either ofthe switches 140er 158, the former of which is part of a safety devicewhich will be later described.

The terminal concealing cabinet 132 isy ars 120 and cabinet designated134 is in the nature of an open box having a rear wall 141, side, topand bottom walls 142', and suitable attach ing angle members 145,whereby it may be secured to the rear wall frame members 146. The lowerwall 142 is slotted at 146 for admitting the cables 120, 121a and 122,within the box and at 147 for the cables 152. A block 147 is` secured tothe rearward face of the wall 141 which when the cover box is attachedto the oven frame pushes inwardly on a button pin 150 of the switch 140.This pin is carried at its4 inner end by a contact block (ordinarilyheld by suitable springs against the outer wall of the switch box andaway from the spring contact plates 153,) thereby closing the separatecircuit 152.

In this manner, I have provided a guard whereby the high tension wiresor cables leading to the bus bars may be effectively enclosed andprotected until it is found necessary to withdraw the heating elementsfrom the oven. The guard box 134 may be removed to allow access to thecable terminals operates the circuit breaker 155. Thus Vin order to getat the oven, it is first necessary to remove the box or guard whichopens the circuit. A n extremely efficient safety device and terminalhousing is thus provided.

Having thus described my invention, I claim 1. In an electrically heatedcore oven, an electric heating element, wall, ceiling and floor membersformed of heat resisting material and a contiguous outer metal skeletonndividually supporting each of said memers.

2. In an electrical oven, an electric heating element, a metal framework comprising a series of joined rectangularframes, each and thisremoval automatically` opens the'separate circuit 152, which in turnadapted to independently support a wall slab of refractory material, allparts of said frame work stopping short of entering the chamber formedby the slabs.

3. In a. core oven having a heating element and side, top and bottomwalls, a heat resisting slab forming the body of one of the walls, acontinuous metal frame embracing the perimeter of such slab and havingflanges lying along the exposed surface thereof, another slab placed atright angles to the first named slab, and a projection on the inner'surface thereof adjacent to the perimetral flange of said first namedslab, whereby a rabbeted joint is formed at the juncture of the slabs.

4. In combination in a core oven having a heating ,-e1e1nent, a comosition wall, a frame adaptedto closely em race the periph`l ery thereofand overhe the margin, a -second wall having a similar frame placed atright angles to the first named wall and overlying the peripheral edgethereof, a

projection rising from the last named wall 1n abutting relation to theinner margin of the first named wall and means whereby a frame member ofone wall is rigidly joined tc'ha lcorresponding frame member of the oer.

5. In combination, in an elect-ric oven, an-

electric heating element, wall slabs placed at right angles to eachother, the'marginal edge of one overlapping the. peripheral edge of theother, a frame member interpo tween the said edges and extending atright angles along the marginal edge of the last named wall member, anangular frame member of thelast named wall member Iinterposed lbetweenthe peripheral edge` of the last named wall member and the margin of thefirst named wall member, means for rigidly securing the frame members`one to embracing. the peri heral edges of the slab and having inturneflanges extending along.

a surface of the slab, a second slab set at right angles to the firstnamed slab, and an int osing frame member partially covering t eperipheral vedge of the second slab v and having inturned flangesextending along a surface thereof, means for securing the frame memberstogether and means for closing the crevices formed between theperipheral edge of the first named slab and the adjacent end of a secondslab.

ments and Ventilating tubescarried by the drawer and air baille platessurmounting the entire structure whereby the heating ele- -ments areprotected from above.

8. In a core oven having -.heat resisting walls and a heatin element, apluralit vof perforated air ba e plates mounted a ove said element, allthe perforations in one of they lates being offset from the perforationsin the others, means for holding the plates in spaced relation to eachother, and means cooperating with said last named means for mounting theplates above the heating element whereby a protection for the elementsand a heat distributor .is provi-ded.

9. In an electrically heated oven a removable drawer, an electricheating element within the drawer, a drawer wall, a plurality ofVentilating tubes carried by the drawer and means consisting of convering slots in the walls of the tubes whereby t e airentering the tubes isevenly distributed through.

out their entire length and is directed toward the center of the oven.

10. Inga core oven having heat resisting walls and a heating element,means for ventilating the oven consisting of a plurality of air shaftsentering the oven at its base, said air shafts having Slots in theirwalls converging toward the entrance of the shaft, and regulatable meansfor rallowing air to pass out of the roof of the oven.

InV testimony whereof, I hereunto aflix my signature. y

FREDERICK A. COLEMAN.

